1. Field of the Invention
This invention relates to troweling devices and more particularly to power driven rotary troweling devices for finishing concrete surfaces.
2. Discussion of the Prior Art
Rotary trowel devices have been used in forming and finishing concrete structures such as floors, driveways and other types of masonary structures. The conventional rotary trowel devices are powered by gasoline engines which severely limits their utility. For example, gasoline powered rotary trowels are unacceptable for inside work because of the toxic and noxious emission gases produced during operation the gasoline engines.
During the troweling operation, the freshly poured concrete, which is in a slurry condition, must be efficiently spread. Thereafter, the concrete is evenly finished during the final stages of troweling. In order to efficiently spread the freshly poured concrete, it is desirable to tilt the troweling blades from the normal horizontal position which is used in the final finishing of the surface. The angle of attack or tilt may be diminished as the concrete begins to set.
There are certain prior art patents which disclose rotary power trowels including U.S. Pat. No. 4,232,980 to Tertinek which is directed to a gasoline powered rotary trowel. While the Tertinek patent also discloses a trowel blade tilt mechanism, it will be noted that the blades are pivoted to a stabilizer ring and are shifted by an actuating system having all the components exposed and located outside the hub of the trowel blade assembly.
U.S. Pat. No. 3,259,033 to Kelly discloses a blade assembly for a trowel machine which the blades are tilted by a blade tilting mechanism in which all of the components are located externally of the hub.
U.S. Pat. No. 2,468,981 to Huffman discloses a trowel machine in which the trowel blades are driven by an output shaft that extends laterally from the power source. The trowel blades are tilted through the use of bevel gears attached to the inner ends of the blade shafts.
U.S. Pat. No. 4,312,603 to Whiteman discloses a power driven twin trowel machine which is structurally and functionally different from Applicant's trowel machine.
Applicant also disclosed a prior prototype troweling machine at an inventor's congress but the prototype machine did not include many of the features of the present machine and did not specifically include the tilting mechanism disclosed in the instant application.